#pragma once

#include <iostream>
#include <string>
#include <vector>
#include <fstream>
#include <unordered_map>
#include <mutex>
#include "util0.hpp"
// #include "log.hpp"

namespace ns_index
{
    struct DocInfo
    {
        std::string title;
        std::string content;
        std::string url;
        uint64_t doc_id;
    };

    struct InvertedElem
    {
        uint64_t doc_id;
        std::string word;
        int weight;
        InvertedElem() : weight(0) {}
    };

    typedef std::vector<InvertedElem> InvertedList;

    class Index
    {
    private:
        std::vector<DocInfo> forward_index;
        std::unordered_map<std::string, InvertedList> inverted_index;

    private:
        Index() {}
        ~Index() {}
        Index(const Index &) = delete;
        Index &operator=(const Index &) = delete;

    public:
        static Index *GetInstance()
        {
            static Index instance;
            return &instance;
        }

        DocInfo *GetForwardIndex(uint64_t doc_id)
        {
            if (doc_id > forward_index.size())
            {
                std::cerr << "doc_id out of range!" << std::endl;
                return nullptr;
            }
            return &forward_index[doc_id];
        }

        InvertedList *GetInvertedIndex(const std::string word)
        {
            auto iter = inverted_index.find(word);
            if (iter == inverted_index.end())
            {
                std::cerr << word << " have no InvertedList" << std::endl;
                return nullptr;
            }
            return &(iter->second);
        }

        bool BuildIndex(const std::string &input)
        {
            std::ifstream in(input, std::ios::in | std::ios::binary);
            if (!in.is_open())
            {
                std::cerr << "sorry, " << input << " open error" << std::endl;
                return false;
            }
            std::string line;
            int count = 0;
            while (std::getline(in, line))
            {
                DocInfo *doc = BuildForwardIndex(line);
                if (doc == nullptr)
                {
                    std::cerr << "build " << line << " error" << std::endl; // for deubg
                    continue;
                }
                BuildInvertedIndex(*doc);
                count++;
                if (count % 50 == 0)
                {
                    std::cout << "当前已经建立的索引文档: " << count << std::endl;
                }
            }
            return true;
        }

    private:
        DocInfo *BuildForwardIndex(const std::string &line)
        {
            std::vector<std::string> results;
            const std::string sep = "\3";
            ns_util::StringUtil::Split(line, &results, sep);
            if (results.size() != 3)
            {
                return nullptr;
            }
            DocInfo doc;
            doc.title = results[0];
            doc.content = results[1];
            doc.url = results[2];
            doc.doc_id = forward_index.size();
            forward_index.push_back(std::move(doc));
            return &forward_index.back();
        }

        bool BuildInvertedIndex(const DocInfo &doc)
        {
            struct word_cnt
            {
                int title_cnt;
                int content_cnt;
                word_cnt() : title_cnt(0), content_cnt(0) {};
            };
            std::unordered_map<std::string, word_cnt> word_map;

            std::vector<std::string> title_words;
            ns_util::JiebaUtil::CutString(doc.title, &title_words);
            for (std::string s : title_words)
            {
                boost::to_lower(s);
                word_map[s].title_cnt++;
            }

            std::vector<std::string> content_words;
            ns_util::JiebaUtil::CutString(doc.content, &content_words);
            for (std::string s : content_words)
            {
                boost::to_lower(s);
                word_map[s].content_cnt++;
            }

#define X 10
#define Y 1
            for (auto &word_pair : word_map)
            {
                InvertedElem item;
                item.doc_id = doc.doc_id;
                item.word = word_pair.first;
                item.weight = X * word_pair.second.title_cnt + Y * word_pair.second.content_cnt;
                InvertedList &inverted_list = inverted_index[word_pair.first];
                inverted_list.push_back(std::move(item));
            }
            return true;
        }
    };
    // Index *Index::instance = nullptr;
    // std::mutex Index::mtx;
}